SASL/SCRAM authentication

lib/client.js

@@ -10,6 +10,7 @@
 var EventEmitter = require('events').EventEmitter
 var util = require('util')
 var utils = require('./utils')
+var sasl = require('./sasl')
 var pgPass = require('pgpass')
 var TypeOverrides = require('./type-overrides')
 
@@ -126,6 +127,28 @@ Client.prototype._connect = function (callback) {
     con.password(utils.postgresMd5PasswordHash(self.user, self.password, msg.salt))
   }))
 
+  // password request handling (SASL)
+  var saslSession
+  con.on('authenticationSASL', checkPgPass(function (msg) {
+    saslSession = sasl.startSession(msg.mechanisms)
+
+    con.sendSASLInitialResponseMessage(saslSession.mechanism, saslSession.response)
+  }))
+
+  // password request handling (SASL)
+  con.on('authenticationSASLContinue', function (msg) {
+    sasl.continueSession(saslSession, self.password, msg.data)
+
+    con.sendSCRAMClientFinalMessage(saslSession.response)
+  })
+
+  // password request handling (SASL)
+  con.on('authenticationSASLFinal', function (msg) {
+    sasl.finalizeSession(saslSession, msg.data)
+
+    saslSession = null
+  })
+
   con.once('backendKeyData', function (msg) {
     self.processID = msg.processID
     self.secretKey = msg.secretKey

lib/connection.js

@@ -191,6 +191,24 @@ Connection.prototype.password = function (password) {
   this._send(0x70, this.writer.addCString(password))
 }
 
+Connection.prototype.sendSASLInitialResponseMessage = function (mechanism, initialResponse) {
+  // 0x70 = 'p'
+  this.writer
+    .addCString(mechanism)
+    .addInt32(Buffer.byteLength(initialResponse))
+    .addString(initialResponse)
+
+  this._send(0x70)
+}
+
+Connection.prototype.sendSCRAMClientFinalMessage = function (additionalData) {
+  // 0x70 = 'p'
+  this.writer
+    .addString(additionalData)
+
+  this._send(0x70)
+}
+
 Connection.prototype._send = function (code, more) {
   if (!this.stream.writable) {
     return false
@@ -421,25 +439,53 @@ Connection.prototype.parseMessage = function (buffer) {
 }
 
 Connection.prototype.parseR = function (buffer, length) {
-  var code = 0
+  var code = this.parseInt32(buffer)
+
   var msg = new Message('authenticationOk', length)
-  if (msg.length === 8) {
-    code = this.parseInt32(buffer)
-    if (code === 3) {
-      msg.name = 'authenticationCleartextPassword'
-    }
-    return msg
-  }
-  if (msg.length === 12) {
-    code = this.parseInt32(buffer)
-    if (code === 5) { // md5 required
-      msg.name = 'authenticationMD5Password'
-      msg.salt = Buffer.alloc(4)
-      buffer.copy(msg.salt, 0, this.offset, this.offset + 4)
-      this.offset += 4
+
+  switch (code) {
+    case 0: // AuthenticationOk
+      return msg
+    case 3: // AuthenticationCleartextPassword
+      if (msg.length === 8) {
+        msg.name = 'authenticationCleartextPassword'
+        return msg
+      }
+      break
+    case 5: // AuthenticationMD5Password
+      if (msg.length === 12) {
+        msg.name = 'authenticationMD5Password'
+        msg.salt = Buffer.alloc(4)
+        buffer.copy(msg.salt, 0, this.offset, this.offset + 4)
+        this.offset += 4
+        return msg
+      }
+
+      break
+    case 10: // AuthenticationSASL
+      msg.name = 'authenticationSASL'
+      msg.mechanisms = []
+      do {
+        var mechanism = this.parseCString(buffer)
+
+        if (mechanism) {
+          msg.mechanisms.push(mechanism)
+        }
+      } while (mechanism)
+
+      return msg
+    case 11: // AuthenticationSASLContinue
+      msg.name = 'authenticationSASLContinue'
+      msg.data = this.readString(buffer, length - 4)
+
+      return msg
+    case 12: // AuthenticationSASLFinal
+      msg.name = 'authenticationSASLFinal'
+      msg.data = this.readString(buffer, length - 4)
+
       return msg
-    }
   }
+
   throw new Error('Unknown authenticationOk message type' + util.inspect(msg))
 }
 

lib/sasl.js

@@ -0,0 +1,146 @@
+const crypto = require('crypto')
+
+function startSession (mechanisms) {
+  if (mechanisms.indexOf('SCRAM-SHA-256') === -1) {
+    throw new Error('SASL: Only mechanism SCRAM-SHA-256 is currently supported')
+  }
+
+  const clientNonce = crypto.randomBytes(18).toString('base64')
+
+  return {
+    mechanism: 'SCRAM-SHA-256',
+    clientNonce,
+    response: 'n,,n=*,r=' + clientNonce,
+    message: 'SASLInitialResponse'
+  }
+}
+
+function continueSession (session, password, serverData) {
+  if (session.message !== 'SASLInitialResponse') {
+    throw new Error('SASL: Last message was not SASLInitialResponse')
+  }
+
+  const sv = extractVariablesFromFirstServerMessage(serverData)
+
+  if (!sv.nonce.startsWith(session.clientNonce)) {
+    throw new Error('SASL: SCRAM-SERVER-FIRST-MESSAGE: server nonce does not start with client nonce')
+  }
+
+  var saltBytes = Buffer.from(sv.salt, 'base64')
+
+  var saltedPassword = Hi(password, saltBytes, sv.iteration)
+
+  var clientKey = createHMAC(saltedPassword, 'Client Key')
+  var storedKey = crypto.createHash('sha256').update(clientKey).digest()
+
+  var clientFirstMessageBare = 'n=*,r=' + session.clientNonce
+  var serverFirstMessage = 'r=' + sv.nonce + ',s=' + sv.salt + ',i=' + sv.iteration
+
+  var clientFinalMessageWithoutProof = 'c=biws,r=' + sv.nonce
+
+  var authMessage = clientFirstMessageBare + ',' + serverFirstMessage + ',' + clientFinalMessageWithoutProof
+
+  var clientSignature = createHMAC(storedKey, authMessage)
+  var clientProofBytes = xorBuffers(clientKey, clientSignature)
+  var clientProof = clientProofBytes.toString('base64')
+
+  var serverKey = createHMAC(saltedPassword, 'Server Key')
+  var serverSignatureBytes = createHMAC(serverKey, authMessage)
+
+  session.message = 'SASLResponse'
+  session.serverSignature = serverSignatureBytes.toString('base64')
+  session.response = clientFinalMessageWithoutProof + ',p=' + clientProof
+}
+
+function finalizeSession (session, serverData) {
+  if (session.message !== 'SASLResponse') {
+    throw new Error('SASL: Last message was not SASLResponse')
+  }
+
+  var serverSignature
+
+  String(serverData).split(',').forEach(function (part) {
+    switch (part[0]) {
+      case 'v':
+        serverSignature = part.substr(2)
+        break
+    }
+  })
+
+  if (serverSignature !== session.serverSignature) {
+    throw new Error('SASL: SCRAM-SERVER-FINAL-MESSAGE: server signature does not match')
+  }
+}
+
+function extractVariablesFromFirstServerMessage (data) {
+  var nonce, salt, iteration
+
+  String(data).split(',').forEach(function (part) {
+    switch (part[0]) {
+      case 'r':
+        nonce = part.substr(2)
+        break
+      case 's':
+        salt = part.substr(2)
+        break
+      case 'i':
+        iteration = parseInt(part.substr(2), 10)
+        break
+    }
+  })
+
+  if (!nonce) {
+    throw new Error('SASL: SCRAM-SERVER-FIRST-MESSAGE: nonce missing')
+  }
+
+  if (!salt) {
+    throw new Error('SASL: SCRAM-SERVER-FIRST-MESSAGE: salt missing')
+  }
+
+  if (!iteration) {
+    throw new Error('SASL: SCRAM-SERVER-FIRST-MESSAGE: iteration missing')
+  }
+
+  return {
+    nonce,
+    salt,
+    iteration
+  }
+}
+
+function xorBuffers (a, b) {
+  if (!Buffer.isBuffer(a)) a = Buffer.from(a)
+  if (!Buffer.isBuffer(b)) b = Buffer.from(b)
+  var res = []
+  if (a.length > b.length) {
+    for (var i = 0; i < b.length; i++) {
+      res.push(a[i] ^ b[i])
+    }
+  } else {
+    for (var j = 0; j < a.length; j++) {
+      res.push(a[j] ^ b[j])
+    }
+  }
+  return Buffer.from(res)
+}
+
+function createHMAC (key, msg) {
+  return crypto.createHmac('sha256', key).update(msg).digest()
+}
+
+function Hi (password, saltBytes, iterations) {
+  var ui1 = createHMAC(password, Buffer.concat([saltBytes, Buffer.from([0, 0, 0, 1])]))
+  var ui = ui1
+  for (var i = 0; i < iterations - 1; i++) {
+    ui1 = createHMAC(password, ui1)
+    ui = xorBuffers(ui, ui1)
+  }
+
+  return ui
+}
+
+module.exports = {
+  startSession,
+  continueSession,
+  finalizeSession
+}

test/buffer-list.js

@@ -36,6 +36,13 @@ p.addCString = function (val, front) {
   return this.add(buffer, front)
 }
 
+p.addString = function (val, front) {
+  var len = Buffer.byteLength(val)
+  var buffer = Buffer.alloc(len)
+  buffer.write(val)
+  return this.add(buffer, front)
+}
+
 p.addChar = function (char, first) {
   return this.add(Buffer.from(char, 'utf8'), first)
 }

test/integration/client/sasl-scram-tests.js

@@ -0,0 +1,41 @@
+'use strict'
+var helper = require(__dirname + '/../test-helper')
+var pg = helper.pg
+
+var suite = new helper.Suite()
+
+/*
+SQL to create test role:
+
+set password_encryption = 'scram-sha-256';
+create role npgtest login password 'test';
+
+pg_hba:
+host    all             npgtest             ::1/128            scram-sha-256
+host    all             npgtest             0.0.0.0/0            scram-sha-256
+
+
+*/
+/*
+suite.test('can connect using sasl/scram', function () {
+	var connectionString = 'pg://npgtest:test@localhost/postgres'
+	const pool = new pg.Pool({ connectionString: connectionString })
+	pool.connect(
+		assert.calls(function (err, client, done) {
+			assert.ifError(err, 'should have connected')
+			done()
+		})
+	)
+})
+
+suite.test('sasl/scram fails when password is wrong', function () {
+	var connectionString = 'pg://npgtest:bad@localhost/postgres'
+	const pool = new pg.Pool({ connectionString: connectionString })
+	pool.connect(
+		assert.calls(function (err, client, done) {
+			assert.ok(err, 'should have a connection error')
+			done()
+		})
+	)
+})
+*/

test/test-buffers.js

@@ -28,6 +28,28 @@ buffers.authenticationMD5Password = function () {
     .join(true, 'R')
 }
 
+buffers.authenticationSASL = function () {
+  return new BufferList()
+    .addInt32(10)
+    .addCString('SCRAM-SHA-256')
+    .addCString('')
+    .join(true, 'R')
+}
+
+buffers.authenticationSASLContinue = function () {
+  return new BufferList()
+    .addInt32(11)
+    .addString('data')
+    .join(true, 'R')
+}
+
+buffers.authenticationSASLFinal = function () {
+  return new BufferList()
+    .addInt32(12)
+    .addString('data')
+    .join(true, 'R')
+}
+
 buffers.parameterStatus = function (name, value) {
   return new BufferList()
     .addCString(name)